DE2947967A1 - METHOD FOR IMPROVING THE SURFACE PROPERTIES OF MOLDED PARTS MADE OF POLYVINYL CHLORIDE RESINS - Google Patents

Description

The invention relates to a method for improving the surface properties of molded parts made of synthetic resins based on polyvinyl chloride, in particular a method for reducing electrostatic charge the surface of molded parts based on polyvinyl chloride resin.

It is known that molded parts made of polyvinyl chloride resins (PVC resins) particularly sensitive to the electrostatic Charging of the surfaces is what not only leads to difficulties in terms of the soiled appearance because of the settling or smearing of dust, but also associated with the unpleasant property is that the human body receives an electric shock when dealing with the electrostatically charged surface comes into contact and there is a risk of spark discharge and noise, e.g. a vinyl record made of polyvinyl chloride resin is peeled off.

Various attempts have been made to obtain a effective method for improving surface properties of molded parts made of polyvinyl chloride resins, e.g. Vinyl records, to make available the electrostatic Surface charging reduced.

For example, it is possible to achieve an antistatic effect by using the surface of the molded parts coated with a surfactant. This procedure is beneficial when the antistatic effect should be reached momentarily and temporarily. However, this method has the disadvantage that the antistatic Effect of short duration, and that the coated

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th surfaces become sticky, which can, for example, lead to the molded parts treated in this way sticking to one another.

It is also known that the surfaces of molded parts made of polyvinyl chloride resins can be electrostatically charged by adding antistatic agents such as surface active agents to the synthetic resin or incorporating these agents into the resin before the molding is formed by compression molding. This method Although it is sufficient in terms of the resistance of the antistatic effect, the effectiveness is exceptional small because the amount of the antistatic agent used is limited. When the amount of antistatic Means is increased so that an antistatic effect sufficient for practical use is achieved Difficulties arise due to the stickiness of the surface, which leads to the moldings stick together and the surface becomes slightly soiled and discolored. In addition, the addition makes itself the antistatic agent also in a disadvantageous reduction in the thermal stability of the molded parts and in the Processability of synthetic resins noticeable.

It has also been proposed to make the surface of molded parts made of polyvinyl chloride resins more hydrophilic to make that the surface is treated or irradiated with a cold plasma, so that the electrostatic charge is partially reduced on the surface. This method has the disadvantage that it is relatively ineffective and the effect achieved does not last long enough.

The invention is therefore based on the object of a new and improved method for reducing the electrostatic Charging on surfaces from molded parts

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To provide polyvinyl chloride resins available, the process should be as effective as possible and the achieved Effect should be achieved as permanently as possible with simple means.

The invention relates to a method for improving the surface properties of molded parts made of polyvinyl chloride resins, where one

(a) the surface of the molded part

treated with a cold plasma of a gas which cannot be polymerized in the plasma state, and

(b) the plasma-treated surface of the molded part with a liquid which is inert to the polyvinyl chloride resin brings together, which may contain a surfactant.

The inventive method has the advantage that it is very easy to carry out, pure water can be used as an inert liquid, the effectiveness is very high is remarkable and the durability of the antistatic surface of the molded article is maintained for more than 2 months remain.

The polyvinyl chloride resins from which the moldings are made can either be made from homopolymers of the Vinyl chloride or various copolymers, which mainly contain 50% by weight and more vinyl chloride, exist. The comonomers which are copolymerizable with the vinyl chloride are known, e.g. the vinyl esters, such as vinyl acetate, acrylic or methacrylic acid and their esters, acrylonitrile, vinylidene halides, olefins, such as ethylene and propylene, etc. In the inventive Processes can use not only binary copolymers but also ternary; or multi-component copolymers are used

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will. Graft copolymers based on polyvinyl chloride resins can also be used be used.

These polyvinyl chloride resins can be used as polymer blends of two or more types as the case may be application, and in some cases they can also be used in admixture with other synthetic resins, e.g. copolymers of ethylene and vinyl acetate, copolymers of styrene and acrylonitrile, copolymers of acrylonitrile and butadiene, copolymers of Methyl methacrylate, styrene and butadiene, copolymers of acrylonitrile, styrene and butadiene, polyamide resins, Caprolactam resins, epoxy-modified polybutadienes, Epoxy-modified polyols and organopolysiloxanes.

The molded part made from the polyvinyl chloride given above can be either flexible or rigid, depending on the presence or the absence of appropriate amounts of plasticizers in the formulation of the molding compound to be processed. The molding compound can also contain other conventional additives that are used in the processing of polyvinyl chloride resins used, e.g. stabilizers, fillers, colorants such as pigments and dyes, UV absorbers, Antioxidants, crosslinking agents, crosslinking accelerators, various types of surface active Means and similar common compounds.

The method for processing polyvinyl chloride resin molding compounds is not limited to certain processes, it covers e.g. extrusion, injection molding, calendering, Compression molding and all other usual processing methods for the production of the desired shapes of the molded parts.

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According to the method according to the invention, the molded part from polyvinyl chloride resin first a treatment or irradiation with a cold plasma of a gas, which is not polymerizable in the plasma state, exposed. The cold plasma used here is known as a gaseous atmosphere full of electrically charged particles, the temperature of the gaseous atmosphere not excessively high compared to the ambient temperature, regardless of the energy of the charged particles is in itself. The cold plasma is generally produced by glow discharge in a gaseous atmosphere Pressure of 0.0013 to 13.33 mbar is generated, the frequency of the power source for the discharge not being limited and ranges from the direct current strength to the microwave range. In particular, there will be a frequency im The so-called high-frequency range is recommended, as this offers the possibility of producing a stable plasma charge consists. In particular, a frequency of 13.56 MHz or 27.12 MHz is used because these frequencies are relatively free from legal regulations governing the radio wave range.

The shape of the molded parts and the arrangement of the electrodes are not limited as long as a stable plasma discharge can be ensured in the space in which the surface of the molded part is irradiated with the plasma atmosphere. For example, a pair of internal electrodes _/ a pair of external electrodes and also coiled electrodes can be used, a coiled electrode being used in particular types of devices for generating plasma. The electrodes can be connected to a high-frequency generator either via a capacitive or electrical coupling or via an inductive coupling.

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The intensity or power density of the cold plasma and the time of the plasma treatment are parameters that interact with one another are interrelated. It is extremely difficult to determine the power density of the cold plasma clearly to be determined because the nature of the plasma atmosphere is extremely complicated and has not yet been fully explored. It Therefore, it is best to set the time of plasma treatment in advance by trial and error depending on the strength of the power source and to determine the molded parts to be treated. In terms of power density, which is the case with most of the commercially available ones Devices for plasma generation is achieved, a treatment time of a few seconds to several times 10 minutes is generally sufficient to complete the To achieve effect. When treating the surface, care must be taken that the surface of the plasma-treated Molded parts are not thermally decomposed due to the heat developed during the plasma discharge.

The other parameters that are taken into account in the plasma treatment are the gaseous components and the pressure of the gaseous atmosphere in which the cold plasma is generated. In order to ensure a stable plasma discharge, the pressure of the gaseous atmosphere should in the device for generating plasma in a range from 0.0013 to 13.33 mbar, preferably 0.013 to 1.33 mbar.

The gases which are filled into the devices for plasma generation should not be polymerizable in the plasma state due to the deposition of polymerized particles on the surface of the plasma-treated molded parts is undesirable. Suitable gases are e.g. inorganic or inert gases such as helium, neon, argon, nitrogen, Nitrogen oxides, nitrogen dioxide, oxygen, air, chlorine,

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Hydrogen chloride, carbon monoxide, carbon dioxide and / or Hydrogen. These gases can either be used alone or as mixtures. It has been found that argon or a gas mixture containing argon is particularly effective, the reasons for this being unknown.

The molded parts irradiated or treated with the cold plasma on the surface are treated with one for polyvinyl chloride resins inert liquid, i.e. a liquid in which the polyvinyl chloride resins are neither dissolved still swell, treated. Such suitable inert liquids are, for example, water, methyl alcohol and dioxane. Water is particularly preferred because it is particularly cheap and particularly effective.

Where the water of the inert liquid is during treatment of the plasma-treated molded parts preferably in the range of 0 to 50 ⁰ C, especially at room temperature. The duration of the treatment with the inert liquid is a few seconds to a few minutes or at least 1 second, although a longer treatment time has no adverse effect. It is not always necessary that the molded part is brought into contact with the inert liquid immediately after the plasma treatment has ended, since the plasma-treated molded part can be brought into contact with the liquid 24 hours after the plasma treatment has ended without any change in effectiveness.

The bringing together of the inert liquid with the molding can be carried out in any conventional manner, e.g. B. by immersing the molded part in the liquid, coating with the liquid by means of spraying or

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Smear, etc. After finishing treatment with the inert liquid, the molded part is dried at a relatively low temperature, e.g. 80 C or less. In general, the molding is dried in air at room temperature or below 50 ° C. in a stream of air. Treatment with the inert liquid can increase the antistatic effect and the persistence of the effect is thereby remarkably improved.

Surprisingly, it has been found that the inventive antistatic effect can be further improved if the inert liquid, e.g. Water or a mixture of water and alcohol, which are used to treat the plasma-treated molded parts made of polyvinyl chloride resins is used, contains a surfactant dissolved, dispersed or emulsified. The concentration of the surfactant in the inert liquid can be below 0.01% by weight, with higher concentrations have no adverse effect on the desired antistatic effect other than loss the relatively expensive surfactant and the need to use relatively large amounts of water for rinsing the moldings which have been treated with the liquid containing the surfactant are. A concentration of more than 50% by weight is not desirable. The concentration of the surface active Average in the inert liquid is preferably from 0.01 to 10% by weight in consideration of the effectiveness and economy.

The surfactants to be used are not limited. For example, cationic, anionic, nonionic and amphoteric surfactants can be used being the cationic surfactants

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are particularly preferred.

As the cationic surfactants, for example, are suitable primary, secondary and tertiary amine salts, quaternary ammonium salts, Pyridinium salts, anionic surface active agents such as sulfonated oils, soaps, sulfonated ester oils, sulfonieites Amide oils, salts of sulfate esters of olefins, ethyl sulfonated salts of carboxylic acids, sulfate ester salts of aliphatic alcohols, salts of alkyl sulfate esters., salts of alkyl sulfonates!., salts of alkyl naphthalene sulfonates , Salts of alkylbenzenesulfonates, salts of succinic ester sulfonates, salts of phosphate esters, anionic surface active agents such as esters of polyhydric alcohols and aliphatic carboxylic acids, ethyloxide addition compounds of aliphatic alcohols, ethylene oxide addition compounds of fatty acids, ethylene oxide addition compounds of aliphatic amino compounds or aliphatic amide compounds, ethylene oxide addition compounds of alkylphenols, ethylene oxide addition compounds of alkyl naphthols, ethylene oxide addition compounds of partial esters of polyvalent ones Alcohols and fatty acids, block copolymers of ethylene oxide and propylene oxide and amphoteric surfactants, like the various kinds of carboxylic acid derivatives and imidazoline derivatives.

The molded parts obtained by the process according to the invention made of polyvinyl chloride resin are, except for the considerably improved and durable antistatic Effect not changed. The method according to the invention is therefore not only suitable for solid molded parts such as records, Computer cards, tapes, etc. are suitable, but also for flexible molded parts, such as films and foils for agricultural applications and other purposes where the problem

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electrostatic charge leads to great difficulties.

The method of the invention is carried out by the following Examples explained in more detail, all parts being parts by weight.

example 1

It was a molding composition of 100 parts of polyvinyl chloride resin with an average degree of polymerization of about 1000, 2 parts of calcium stearate and 2 parts of zinc stearate are kneaded on a roller mill for 10 minutes at 180.degree and then processed by compression molding at 185 C to a sheet with a thickness of 0.5 mm.

A piece of the above sheet was placed in a plasma generating device and both surfaces of the Lanes were then irradiated with a cold plasma for 10 minutes. The cold plasma was by means of an electric Discharge produced using a high frequency current of 50 watts while the pressure is within the Device was set to 0.399 mbar and argon under reduced pressure with simultaneous evacuation Seconds immersed in water at room temperature and at. Air dried at room temperature.

The surface properties of the thus prepared water-and plasma- treated web (Sample 1) were compared with the characteristics of another sample of the same web, which was not atier _/ treated with a cold plasma with ^ hater (sample 2). The measurement results were taken directly after

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the treatments and after a break of 6 months. Table 1 shows the measurement results, namely the distance from which cigarette ash is attracted to the surface charged by friction,. the specific resistance of the surface measured at 25 C in an atmosphere of 50% relative humidity and the electrostatic charge voltage by rubbing with a rotating static tester (test conditions: rubbing cloth made of cotton, load 200 g, 750 revolutions / minute, rubbing time 30 seconds, relative Air humidity 25% at 25 ° C
in summary.

25% at 25 ° C and contact angle of water at 23 ° C)

Example 2

The polyvinyl chloride resin sheet was produced as in Example 1, with the exception that the molding compound was made from 100 parts of the same polyvinyl chloride resin, 1.5 parts of cadmium stearate and 0.5 parts Barium stearate.

A piece of the web was placed in the plasma generator and both surfaces of the web were then treated with a cold plasma for 5 minutes, with the high frequency electric current at 100 watts increased and the pressure inside the device was set to 0.266 mbar, while a mixed gas of 90:10 Volumes of argon and carbon monoxide was passed through the device.

The plasma treated web was then immersed in a 1% aqueous Anionic surfactant solution (TB-160 from Matsumoto Yushi Co., Japan) for 3 seconds immersed at room temperature, then with water

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rinsed and air dried at room temperature.

The measured surface properties of the plasma-treated and solution treated web (sample 3) and the properties of another sample of the same web that treated with the plasma but not with the surfactant solution (sample 4) are as follows Table summarized, namely the measurement results directly after the treatment and the results after one 6 months break.

Example 3

A polyvinyl chloride resin sheet was produced by following the procedure of Example 1 with the exception that the resin molding compound to be processed into a web with a further proportion of 0.2 parts of a cationic surface-active agent Using (Catanac SN) was mixed per 100 parts of polyvinyl chloride resin. The terms of the Treatments with the cold plasma were the same as in Example 1, except that the pressure of the Argon was 0.266 instead of 0.399 mbar.

The plasma treated web was then immersed in a 1% aqueous solution of an anionic surfactant for 3 seconds Dipped by means and then rinsed with water and air dried.

The surface properties of the plasma-treated and solution treated web (sample 5) and the surface properties Another sample of the same track, which was with the plasma but not with the aqueous surface-active Solution (sample 6) are summarized in Table 1.

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Example 4

A molding compound made of 100 parts of polyvinyl chloride resin was obtained having an average degree of polymerization of about 700, 1.0 part of an epoxidized soybean oil, 1.0 part Dibutyltin mercaptide, 0.3 part calcium stearate and 0.1 part graphite for 10 minutes at 170 ° C on a roller mill kneaded and then processed by compression molding at 180 C to a sheet with a thickness of 0.5 mm.

The plasma treatment of the above web was carried out essentially as described in Example 1, but with the Exception that the pressure inside the device was 0.533 mbar instead of 0.399 mbar, the current strength to 100 watts and the plasma treatment time was 5 minutes instead of 10 minutes. The plasma-treated web was then sprayed with a 0.03% aqueous solution of a cationic surfactant (Ameet 105), rinsed with water and allowed to air dry.

The measurements to determine the surface properties were carried out as described in Example 1 (sample 7) and then the results were compared with another piece the same lane treated with the plasma but not with the surfactant solution was (sample 8) compared. The measurement results are summarized in Table 1.

Example 5

A molding composition composed of 50 parts of polyvinyl chloride resin, 50 parts of vinyl chloride-vinyl acetate copolymer, 1.0 part of an epoxidized soybean oil, 1.0 part of dibutyltin mercaptide and 0.3 part of calcium stearate for 10 minutes

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160 C kneaded on a roller mill and then by means of compression molding at 170 ° C to a sheet with a thickness of 0.5 mm processed.

The plasma treatment of the above web was carried out essentially as described in Example 1 with with the exception that the pressure inside the device was 0.266 mbar, the amperage was increased to 250 watts and the treatment time was 2 minutes. The plasma treated web was then treated with a 0.1% sprayed with an aqueous solution of a cationic surfactant (Emal TD), then rinsed off with water and air dried.

The surface properties of the plasma and solution treated Web (Sample 9) were measured in the same manner as described in Example 1, and then were these properties with those of another sample from the same path, but not with the plasma but not with the surfactant solution had been treated (sample 10) compared. The measurement results are summarized in Table 1.

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Table 1

sample £ nzugsa, batand
for
Cigarette ash
(cm) specific
resistance
e the waiter
area (Λ) 5X1Q11 6X10 ¹³ 5X10 ¹³ • Charging
tension
at the Rei
ben (V) -Contact
angle
of what
ser (degree 25th 23 53 58 direct
after
Treat
lung 1 0 5X1011 0 i 3X1O ¹⁰ 0 3X10 ¹¹
t 7.3X1010 710 21 28 2100 j 51 280 j 45 I.
I.
6 months
after
Treat
lung 2 1 5X1O12 1 '8X1O ¹¹ 2 7X10 ¹³ 1100 26th 43 170 i 43
I. 2300 3 0 9X10 ¹⁰ 0 8X10 ¹¹ 0 3X10 ¹⁰ 250 22nd 370; 27 2000 4th 1 7X1012 2 j 2 1 3X10 ¹³ 1250 31 2100 j 45 5 0 2X10 ¹⁰ 3 0 5X10 ¹⁰ 150 19th 280 6th 0 3.3X10 ¹¹ 4th 2 5X10 ¹³ 350 43 7th 0 I 1X1O ¹⁰
) 5 0 80 38
1 8th 1 6th 2 980 28 Λ 7th 120; 37. 10 8th 1050 1 9 1000 10 2300

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Example 6

There were records in a record press at a pressing temperature of 165 C from a preheated to 140 ° C Polyvinyl chloride resin molding compound produced, the 100 parts of vinyl chloride-vinyl acetate copolymer, 1.0 part of a epoxidized soybean oil, 0.2 parts of a cationic Surfactant (Catanac SN) 1.0 part dibutyltin mercaptide and 0.3 part calcium stearate.

The records were placed in a device for generating a plasma and both surfaces of the Plate were treated for 5 minutes with a cold plasma, with an electrical discharge of a high frequency Current of 100 watts was used while the pressure in the device was adjusted to 0.266 mbar and argon was bubbled through the device under reduced pressure. The plasma-treated records were immersed in a 0.1% aqueous solution of a nonionic surfactant (Denon 1886) dipped, then rinsed and air dried.

The S / N (signal / noise) ratio of the above plasma-treated and solution-treated records (sample 11) and the S / N ratio of a comparative record recorded with a cold plasma but not with an aqueous one Surfactant solution (Sample 12) was treated in the introduction parts of the Plate immediately after the treatments, after the initial wear, i.e. the wear after the four to playing the record six times, after 100 uses and after 500 uses certainly. The results obtained are as follows

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Table 2 summarized, in which also the adhesion test results are included with the cigarette ash.

The results in Table 2 show that the record treated according to the invention (sample 11) in contrast to Comparative sample (sample 12) a stable S / N ratio with a considerable improvement in wear resistance has, and the record treated according to the invention has a lower tendency to electrostatic charge.

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Table 2

O CaJ O O

CD CO

12th Tightening distance S / N ratio and , 9 after
Initial
use Difference (db) after 500-
one-time Be
use AS / N after
11
12th for zi
garette ash
(cm) before the
use
(Play) , 0 S / N AS / N after 100-
one-time Be
use S / N +0.1 S / N , 0
, 7 56.7 -0.2 S / N AS / N 57.0 -0.3 sample O 56 56.5 -0.5 56.8 -0.1 56.7 +0
-0.1 0 57 56.8 -0.2
56.5 -0.2 56.8 -0.2 57.0
56.6 0
1.5 57
56 56.9 -0.1
56.5 -0.2 right after
the loading plot 6 months
the Be
plot

NJ

to

LO O ~>

Example 7

The polyvinyl chloride resin sheet was produced as described in Example 2 and as described in Example 1 exposed to plasma treatment. The plasma treated web was carefully washed by placing the web in running water was immersed, then the sheet was air-dried for 24 hours.

It became the electrostatic charge of the above plasma and water treated sheet (sample 13) and the charge another part of the same lane which has been subjected to water treatment but not plasma treatment (sample 14) has been subjected, measured by determining the rubbing movements on the surface of the web with a Cotton cloth to cigarette ash placed 3 cm from the web from the surface of the Web was tightened shortly after the rubbing treatment and after one year of storage of the web. The results are summarized in Table 3.

Example 8

It was a molding compound of 50 parts of vinyl chloride-vinyl acetate copolymer, 50 parts of a polyvinyl chloride resin, 1.5 parts of calcium stearate and 1.5 parts of zinc stearate kneaded at 170 ° C on a roll mill, and then a sheet was formed by compression molding at 175 ° C a thickness of 0.5 mm.

A portion of the web was placed in a plasma generator and both surfaces were exposed to Treated with a cold plasma for 30 seconds by means of an electrical discharge of a high-frequency current

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of 300 watts, while the pressure is set to 0.399 mbar and nitrogen gas with reduced pressure through the device was directed. The plasma treated web was then mixed into a 5% aqueous solution for 5 seconds surface-active substances from a sodium alkylbenzenesulfonate and dipped in a higher alcohol, then rinsed with water and allowed to air dry.

With the above plasma and solution treated sheet (sample 15), similar tests were carried out on the attraction of cigarette ash according to example 7 and compared with the values of another part of the same trajectory using the same solution of the surfactant but had not been treated with a plasma (sample 16). The results of this Experiments are summarized in Table 3.

Example 9

It was a molding composition of 100 parts of vinyl chloride-vinyl acetate copolymer, 1.5 parts of calcium stearate, 1.5 parts of zinc stearate, 0.1 part of a cationic surfactant Kneaded by means of (Catanac SN) and 0.1 part of graphite for 10 minutes at 160 ° C on a roller mill and a sheet of 0.5 mm thickness was then produced therefrom by means of compression molding at 165.degree.

A portion of the above web was placed in a plasma generating device and both surfaces were treated with a cold plasma for 2 minutes, the electrical discharge using a high-frequency current of 150 watts was made, the pressure in the device was 0.399 mbar and a

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Mixture of argon and carbon monoxide in a volume ratio of 90:10 under reduced pressure through the device was directed.

The plasma treated web was mixed on both surfaces with a 40% aqueous solution of a Sodium alkylbenzenesulfonate / higher alcohol surfactant coated, then immediately coated with Rinsed with water and allowed to air dry.

The above sheet (sample 17) and another piece of the same sheet that contained the surfactant but has not been treated with the plasma (sample 18) was the same test experiments with regard to the Attraction of cigarette ash, as described in example 6, subjected. The results of these tests are summarized in Table 3.

Table 3

Sample Number of rubbing movements for the attraction of cigarette ash

after treatment after 12 months

100 - 200 1

more than 500 1

more than 500 1

13th 100 - 200 14th 3 15th more than 500 16 3 17th more than 5OO 18th 3

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Claims (10)

Process for improving surface properties of molded parts made of polyvinyl chloride resins Claims ylt process to improve surface properties of molded parts made of synthetic resin based on vinyl chloride, characterized in that (a) the surface of the molded part with a cold plasma of a gas which cannot be polymerized in the plasma state is, irradiated and (b) the plasma-treated surface of the molded part with a liquid that is inert to synthetic resins Vinyl chloride based matches. 2. The method according to claim 1, characterized in that one 03002W07 6 9 ORIGINAL INSPECTED 29A7967 (a) the surface of the molded part with a cold plasma of a gas which cannot be polymerized in the plasma state is, irradiated and (b) the plasma-treated surface of the molded part with a surface-active agent containing one brings together aqueous solution. 3. The method according to claim 1 or claim 2, characterized in that the gas which has no polymerizability in the plasma state, argon or a mixed gas containing argon is used. 4. The method according to claim 1, characterized in that the liquid opposite to synthetic resin Vinyl chloride base is inert, water is used. 5. The method according to claim 1, characterized in that the plasma-treated surface of the molded part expose for at least 1 second to the liquid inert to vinyl chloride based synthetic resins. 6. The method according to claim 2, characterized in that that the plasma treated surface of the molded part for at least 1 second of a surfactant containing aqueous solution. 7. The method according to claim 2, characterized in that there is a cationic surface-active agent surfactant used. 030024/0769 8. The method according to claim 2, characterized in that the surfactant is in the aqueous solution is present at 0.01 to 10% by weight. 9. The method according to claim 1, characterized in that the plasma-treated surface of the molded part with the liquid, which is inert to vinyl chloride-based plastics, within 24 hours of the Bringing termination of treatment with the cold plasma. 10. The method according to claim 2, characterized in that the molded parts after treatment with the aqueous Solution containing a surface-active agent, rinsed off and dried at a temperature below 80 ° C. 030024/0769